The present invention relates to a spring connector mounted on and soldered to a board, or a connector configured by mounting a spring connector onto a board by soldering, in which a distal end of an electrically conductive metal tube can be positioned at sufficiently low level on the surface of the board, e.g. the same height as a surface of the board.
Referring to FIG. 9, a structure of a connector in the related art in which a spring connector is mounted on a board will be described. FIG. 9 is a vertical sectional view of the connector in the related art. In FIG. 9, an electrically conductive metal tube 10 is formed by providing a bottomed hole 10a in electrically conductive metal material. Moreover, a small diameter tube part 10c having a smaller outer diameter is formed at a distal end side of the conductive metal tube 10 near an opening 10b of the bottomed hole 10a, and a large diameter tube part 10d having a larger outer diameter is formed at a backward end side thereof. A spring coil 12 and further, a plunger 14 are inserted into the bottomed hole 10a. Then, the opening 10b of the bottomed hole 10a is narrowed by caulking, so that the plunger 14 can freely move in an axial direction but may not slip out, in a state where its tip end portion is protruded from the opening 10b. In this state, the spring coil 12 is contracted, and the plunger 14 is elastically urged in a protruding direction. In this manner, the spring connector 16 is constructed. Then, the spring connector 16 is mounted on a surface of a board 18, and a backward end face of the conductive metal tube 10 is soldered to the board 18 as a soldering part, whereby the connector is constructed. In this case, for enabling the conductive metal tube 10 to stand by itself on the surface of the board 18, the large diameter tube part 10d is formed so that an area of the backward end face of the tube 10 may be increased. An art employing the connector in this related art is disclosed in JP-A-2003-217726.
In the connector of the related art as shown in FIG. 9, a height h1 from the surface of the board 18 to the distal end of the conductive metal tube 10 is large. Therefore, a connector in the related art as shown in FIG. 10 has been proposed, as an art for making the height smaller. FIG. 10 is a vertical sectional view of the connector in the related art. In describing the connector in the related art referring to FIG. 10, the same or substantially the same members as the members as shown in FIG. 9 will be denoted with the same reference numerals, and overlapped description will be omitted. The connector in the related art as shown in FIG. 10 is different from the connector in the related art as shown in FIG. 9 in the following points. To begin with, a backward end part of the large diameter tube part 10d at the backward end side of the conductive metal tube 10 has a reduced outer diameter, and a flange-like portion 10e is formed at an intermediate position in the axial direction. The board 18 is provided with a through hole 18a which has such a diameter that the reduced outer diameter portion at the backward end side of the conductive metal tube 10 is allowed to be inserted, but the flange-like portion 10e is not allowed to pass. Moreover, an electrically conductive metal foil or the like is applied to an inner peripheral wall of the through hole 18a of the board 18, so that the solder in a molten state may easily enter into a gap between the through hole 18a and an outer peripheral face of the conductive metal tube 10 by capillary phenomenon. The backward end part of the conductive metal tube 10 having the reduced outer diameter is inserted into the through hole 18a of the board 18 from a front face side, and the flange-like portion 10e is fixed by soldering to the surface of the board 18, whereby the connector is constructed.
In the connector of the related art as shown in FIG. 10, a height h2 of the distal end of the conductive metal tube 10 projected from the surface of the board 18 is made smaller by an amount of the backward end part of the conductive metal tube 10 inserted into the through hole 18a of the board 18. As the results, the height h2 can be made considerably smaller than the height h1 of the distal end of the conductive metal tube 10 from the surface of the board 18 in the connector of the related art as shown in FIG. 9. However, since, in some cases, the related art as shown in FIG. 10 does not sufficiently satisfy a recent demand of further down sizing of electronic apparatuses, it has been required that the height of the distal end of the conductive metal tube 10 from the surface of the board is made further smaller.